Développement de méthodes analytiques pour l’évaluation de l'impact de l'industrie de fertilisants chimiques sur le milieu marin / Development of Analytical methods for the evaluation of the impact of phosphate fertilizer industry on marine environment

Chumbo (Pb) é um elemento tóxico ao qual estão associadas diversas doenças que afligem o ser humano. Dessa forma, o desenvolvimento de novas metodologias para a determinação de Pb no sangue traz uma importante contribuição na monitoração humana exposta a este metal. No presente estudo, é apresentado uma metodologia nova para determinação de Pb utilizando-se a técnica fingerstick com filtro de papel em conjunto com a espectrometria de massas de alta resolução em fonte de plasma indutivo (HR/ICP/MS). Os resultados encontrados mostraram-se robustos para uma digestão total de cerca de 0,1 g de sangue, em valores de referência, e níveis de chumbo inferiores a 5 μgdL-1. O presente método é pouco intrusivo permitindo a coleta e transporte das amostras à longa distância sem perda de integridade e/ou estabilidade. Dessa forma traz uma importante contribuição para o monitoramento da exposição do metal principalmente no atendimento às comunidades distantes. / Lead (Pb) is a toxic element to which several diseases affecting human beings are associated. Therefore, the development of new methodologies for the Pb determination in blood represents an important contribution to monitor human exposition to this metal. In the present study, a new methodology for Pb determination is presented using fingerstick techniques for sample collection and lead detection by using a high resolution inductively coupled plasma mass spectrometry technique. The results are robust for total digestion of 0.1 g of deposited blood and lead levels below to 5 μgdL-1. This method is less intrusive in comparison with the traditional ones. It allows the collection and transport of samples over long distances without loss of integrity and / or stability. Therefore, it brings an important contribution for monitoring the exposure of this metal mainly in the attendance to remote communities.

Rapakivi and alkali feldspar phenocrysts from the Deer Isle Granite Complex were investigated using in situ trace element and Pb isotope geochemistry to see if magma mixing or isothermal decompression was responsible for their formation. Pb isotope and trace element profiles, along with CL imagery of quartz phenocrysts, indicate compositional changes in the magma chamber occurred during rapakivi and alkali feldspar growth. Repeated episodes of magma mixing/replenishment by relatively isotopically primitive and LREE enriched magmas (along with hybridized variations with the host magma) created localized disequilibration. Alkali feldspar phenocrysts proximal to these zones of thermal perturbation were first resorbed and then mantled by plagioclase. Entrainment back into this zone of mixing caused multiple mantles of plagioclase to form on some phenocrysts. For grains more distal to these zones of mixing, complete disequilibration of the grain did not occur and continued growth resulted in Ba-rich alkali feldspar mantles over Ba-poor alkali feldspar cores. As crystallization of the chamber continued along solidification fronts, batches of cooler crystal-rich magmas settled en masse to the floor. Disaggregation of these batches during settling, and subsequent accumulation on the chambers floor, brought grains with disparate crystallization histories together. Filter pressing of the cumulate pile flushed highly evolved fluids out from interstitial pores. Small amounts of evolved liquid, trapped interstitial to the cumulate, formed LREE depleted albitic rims on some grains. The crystallization, transportation and juxtaposition of rapakivi, mantled alkali feldspar and plagioclase phenocrysts suggests that a relatively large and active magma chamber, periodically recharged by batches of melt, must have existed.

The koi carp Cyprinus carpio is an invasive fish that has reached high numbers and biomass in the North Island of New Zealand, particularly in the Waikato region. This species has a variety of negative effects on aquatic ecosystems, increasing turbidity, uprooting aquatic macrophytes, and affecting water column nutrient levels. Recent research in Australia and New Zealand has shown that adult carp, though largely restricted to small scale movements, are capable of moving long distances. Movement in adult carp may be underestimated by these studies, and comparatively little is known about the movement of smaller carp. This study examined the feasibility of using laser ablation otolith microchemistry to track koi carp movement and identify spawning areas. Water samples from six locations (Lake Waahi, Lake Whangape, Lake Waikare, the Whangamarino River, and the Waikato River at Aka Aka and Rangiriri) were analysed using inductively coupled plasma mass spectrometry (ICP-MS). Significant differences between sites were found in the water concentrations of many elements. Koi carp were collected from the above locations, as well as from Opuatia Stream, Pungarehu Stream, the Maramarua River and Lake Hakanoa. The elemental concentrations in the asteriscus otoliths were analysed using laser ablation inductively coupled plasma mass spectrometry (LA‐ICP-MS). Elemental concentrations in the edges and nuclei of adult koi carp and the edges of young-of-the-year (YOY) koi carp were significantly different between capture sites. No significant differences were found in elemental concentrations between sites in the nuclei of YOY koi carp. A discriminant function analysis (DFA) was carried out using the otolith edge elemental signatures of koi carp. The model used Ba, Sr, Mg, Rb and Zn concentrations to differentiate between four capture locations: the Waikato River, Pungarehu Stream, Lake Waahi, and Lake Waikare and Pungarehu Stream. The DFA was able to correctly predict the capture location of 82% of koi carp using their otolith edge elemental signatures. The classification functions created using koi carp otolith edge signatures were then used as a training set to classify otolith nucleus signatures. The otolith nuclei of 80% of YOY koi carp were classified to their site of capture, suggesting they had not moved between locations. The majority of adult koi carp caught at Lake Waikare, Whangamarino River, Pungarehu Stream and Opuatia Stream had nucleus signatures matching their capture sites, indicating that these fish originated from their capture location. Koi carp from other sites likely moved there from another location. The majority of adult koi carp (88%) caught at the Waikato River at Rangiriri had otolith nucleus signatures matching Lake Waikare and Pungarehu Stream. Adult koi carp caught at Lake Waahi and the Waikato River at Aka Aka had otolith signatures corresponding to a range of locations. While some areas (Lake Waikare, Pungarehu Stream) appear to have resident koi carp populations that likely originated there, others (Lake Waahi, the Waikato River) appear to have koi carp populations of mixed origin. These results indicate that Lake Waikare, Pungarehu Stream and the Whangamarino River may be important sources of koi carp recruits in the lower Waikato region.

Cereal based foods, including breakfast cereals and Asian noodles are potentially good sources of selenium. Although these are major foods consumed globally, their contribution to dietary intakes of selenium is unclear. In addition, there has been very limited research into the effect of processing steps on the analysis and apparent retention of selenium. The low levels typically present in foods and the presence of multiple chemical forms of the element provide significant analytical challenges to research in this area. Therefore, the aims of this study were firstly to evaluate and validate procedures for extraction and measurement of selenium in wheat flour. Secondly, the procedure has been applied to analysis of selenium in cereal foods. The methods employed were firstly validated using wheat-based reference materials and then samples of various breakfast cereals as well as different styles of Asian noodles were analysed. Selenium was extracted using closed- v essels by microwave digestion with a mixture of nitric acid and hydrogen peroxide, followed by determination through Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). The optimum conditions for selenium determination in cereal based foods involved the digestion of 0.1 g samples using 1 mL of nitric acid and 1 mL of hydrogen peroxide. The addition of 1% (v/v) methanol was found to enhance the sensitivity of the ICP-MS system. Two particular isotopes of selenium (77 and 82) could be effectively employed in the analysis and there was no significant decrease in total selenium in the digested extracts during storage for up to twelve days under refrigeration and room temperature conditions. Good precision levels were obtained and the total selenium levels in the breakfast cereal samples ranged from 0.059 to 0.378 µg/g. For white salted noodles the values varied between 0.057 and 0.712 µg/g, for yellow alkaline noodles, 0.109 to 0.265 µg/g and 0.077 to 0.284 µg/g for fried instant noodles. There was no appar ent change observed in total selenium during the processing of fried instant noodles, indicating the effectiveness of the extraction method developed here. It is concluded that microwave digestion is an effective approach to sample extraction, the procedures validated in this study are suitable for cereal grain foods and that there is considerable variation in the selenium contents of breakfast cereal and Asian noodle products.

Antimony is naturally occurring in the environment. The assessment of human exposure to environmental antimony is limited. This research focuses on the determination of antimony in water, beverages, and fruit. First, we explored whether there is a correlation between arsenic and antimony in water samples with a wide range of arsenic and antimony concentrations. The results showed absent correlation. Second, we determined antimony concentrations in bottled beverages including bottled water, soft drinks, juices and alcoholic drinks from Canada. The results showed that the antimony in most of these samples were below the Health Canada Guideline (6 g/L) for drinking water except one alcoholic drink which contains 7 g/L antimony. Further analysis of lemons and oranges using high performance liquid chromatography (HPLC) separation and inductively coupled plasma mass spectrometry (ICP-MS) detection demonstrated the presence of antimonycitrate species in these fruits, which has not been reported in literature.

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Closed-vessel microwave assisted volatilization of Ge, Se, Si and quartz as their volatile compounds , for the determination of trace impurities in high purity Ge, Se, Si and quartz is reported. The volatilization of Ge is 98.7% using vapors of aqua regia whereas vapors generated from 72:1 ratio of HCl:HNO3 is required to volatilize 99.2% of Se. Using vapor of 10:5 ratio of HF:HNO3 , the volatilization of Si is 98.6%, and the volatilization of quartz is 99.0% with 15:3 ratio of the mixed acids. The recoveries of Mg, Cr, Mn,, Ni, Co, Cu, Zn, Cd, Ba and Pb are in the range 83-116%. Determinations are carried out using inductively coupled plasma mass spectrometer with Dynamic Reaction CellTM (DRC ICP-MS). Isobaric interferences, due to the formation of 40Ar12C+, 35Cl16OH+, 40Ar16O+ and 40Ar74Ge+ on the determination of 52Cr+, 56Fe+ and 114Cd+, have been alleviated using ammonia cell gas in DRC. Matrix volatilization using in situ generated acid vapors in closed containers resulted in sub ng mL-1 experimental blanks. Method detection limits are in the low ng g-1 level. The methods developed have been applied to determine trace impurities in high purity Ge, Se, Si and quartz samples.